The present invention relates to a laser beam arrangement and, more particularly, to a laser beam axis-monitoring apparatus.
Laser beams are generally employed for welding, fusion, surface treatment, etc. of a workpiece wherein the laser beam is generated by a laser oscillator which includes a discharge tube and two mirrors, with the discharge tube being filled with a laser medium. The two mirrors are a total-reflection mirror and an output-reflection mirror, with each of the mirrors being mounted at respective ends of the discharge tube.
In using, for example a CO.sub.2 laser oscillator in, for example, welding, drilling, cutting, etc., one problem which arises is that a wavelength of the CO.sub.2 laser is in an invisible region so that the beam of the laser cannot be observed. Because of the lack of visible beam of light, considerable difficulties arise in, for example, positioning of the work piece which is necessary to ensure a proper processing thereof.
In U.S. Pat. No. 3,892,488, an arrangement is proposed for enabling a proper position of a work piece to be processed. More particularly, in the proposed construction, a He-Ne laser, having an oscillation wavelength in the visible region so as to provide for a visible beam of light is employed and, during a positioning of the workpiece, light from a light generator is projected onto an intermediate reflection mirror which is inserted between the laser oscillator and the workpiece with the light being superposed on an optical path of the laser beam. A diameter of the beam of light is approximately 1 mm and is as small as about 1/20 to 1/50 of a diameter of the beam of the laser. Therefore, the intermediate reflection mirror and light generator are arranged in advance so that a center axis of the laser beam and axis of the light ray coincide with each other.
In order to permit a laser oscillator to oscillate under the best conditions, it is often required that, the inclination of the total reflection mirror be changed so as to maximize the power of the laser. However, when the inclination of the total reflection mirror has been changed, the optical path of the laser beam naturally changes.
In the laser beam access monitoring apparatus proposed in the aforementioned United States Patent, when the inclination of the total reflection mirror has been changed, the path of light from the light generator has not been changed because the light is reflected by the intermediate reflection mirror and led to the workpiece. However, with a change of the inclination of the total reflection mirror, the somewhat troublesome operation of bringing the optical paths of the laser beam and light beam into coincidence is once again required and it is impossible to always monitor the axis of the beam of the laser beam or the projected position of the laser. Therefore, the possibility arises that the workpiece will not be processed or worked in the desired manner.